This invention relates to a multiple universal joint type of coupling device for drive lines having substantially or totally homokinetic power drive features.
It is known that a gimbal or universal joint is commonly employed to transfer rotary motion between two shafts placed at an angle to each other, and although its performance is fairly efficient, alternating rotational velocity variations do occur between such shafts. This drawback has somewhat restricted the application of this type of joint or gimballed device in many an industrial field, such as the automotive industry, where it is required that the rotary motion be transferred in a perfectly smooth or homokinetic way throughout the 360.degree. of rotation of the joint.
Intensive research work has been devoted to the subject in order to overcome the above difficulty. The one drive line coupling device so far developed which has proved successful in part and has been adopted in the industry, is the dual universal joint type. However, the optimum operation of this known drive line coupling device is subject to serious limitative conditions, such as the coplanarity of the three rotating shafts and the symmetry with respect to a centerplane orthogonal to the intermediate shaft member, and these requirements, in turn, involve a bulky and costly construction.